Conventionally, an internal combustion engine may be equipped with an evaporative system. The evaporative system may include a fuel vapor canister accommodating a charcoal filler to absorb fuel vapor produced in a fuel tank. The evaporative system may be configured to send the absorbed fuel vapor into an intake manifold of the engine thereby to burn the absorbed fuel vapor in combustion chambers of the engine. In this way, the evaporative system may restrict fuel vapor produced in a fuel tank from escaping as fuel vapor emission to the atmosphere. The evaporative system may include a transmission system such as a ejector to draw absorbed fuel vapor from the fuel vapor canister into the combustion chambers of the engine. It may be conceivable that the transmission system may have a failure such as breakage in its conductive passage to cause leakage of fuel vapor therethrough.